Monkeypox: Some Keys to Understand This Emerging Disease

SIMPLE SUMMARY: Monkeypox has entered our lives when we have not yet fully recovered from the SARS-CoV-2 pandemic. This close relative of the smallpox virus was restricted to tropical Africa, except on rare occasions when it caused human cases in the US, UK, Singapore, or Israel. Cases have recently been identified in multiple countries in at least the Americas, Europe, Asia and Australia. Fortunately, it produces much milder clinical symptoms and a much lower mortality rate than smallpox, but even so, we have learned not to overlook any possible pathogen, and there are many unknowns about the disease. What population groups does it affect? Could it cause a pandemic? What is the animal reservoir? Do animals suffer from monkeypox as much as humans? ABSTRACT: In 1958, several monkeys in a Copenhagen laboratory developed a skin rash from which an orthopoxvirus could be isolated, which was named monkeypox virus (MPXV). However, the natural animal reservoir for MPXV is thought to be a rodent. The first human case occurred in 1970, and the incidence has increased progressively throughout the years. Starting May 2022, the number of cases outside Africa has soared, especially in Western Europe. There are two clades of MPXV, Congo Basin, with higher virulence and mortality, and Western Africa (WA). MPXV from the present outbreak has been proposed to be classified as Clade 3, distinct from the WA clade by at least 50 substitutions, which may increase human-to-human transmissibility. Most cases correspond to men in their 30s who have sex with men, and the possibility of sexual transmission is under investigation. Though there is no evidence of human-to-animal transmission, pets of positive human cases may be classified as low risk, including dogs, cats, and birds, who can be quarantined at home, and high risk, such as pet rabbits or mice, who should be isolated in official laboratories for observation. The current epidemiological data do not support the risk of a pandemic.